As more and more drivers choose to “go green,” a greater number of alternative fuel vehicles are hitting the roadways. Vehicles that run exclusively on batteries, hybrid vehicles that combine a gas engine with an electric motor, as well as simpler means of travel such as bicycles are growing ever more popular.
Unlike traditional automobiles and gas-powered vehicles, battery-powered, electric-powered, and man-powered modes of transportation lack the noise associated with combustion engines. The silent operation of these vehicles can pose a problem for pedestrians and others who have grown accustomed to identifying the presence of a vehicle nearby by listening for engine noise. A pedestrian looking the wrong way at an intersection may be surprised by the quiet passage of a hybrid vehicle. Even worse, the pedestrian may start crossing the street in front of the quiet vehicle before noticing its presence, forcing the driver to take evasive action and risking bodily injury to both the driver and the pedestrian.
The driver of a vehicle equipped with a horn may try to compensate for the lack of engine noise by beeping the horn to announce the presence of the vehicle. However, such horns are often loud and startling, especially when heard unexpectedly. A pedestrian may be distressed upon hearing the sound of an unexpected horn and may put himself in greater danger by reacting too quickly, for example tripping on the curb or moving into other vehicle traffic. Furthermore, the harsh sound of a vehicle horn, often associated with traffic jams, angry drivers, and road rage, may create a hostile and negative atmosphere for both the driver and the pedestrian.
Thus, there is a need for a system that provides pedestrians with a gentler indication of the presence of a vehicle, such as a quiet vehicle.